So, what are some things I should be doing (documenting?) now, as a happy and well-performing at-will US-based employee, so that I can have legal standing for a

So, what are some things I should be doing (documenting?) now, as a happy and well-performing at-will US-based employee, so that I can have legal standing for a better "redundancy package" than what is offered, if I'm terminated, later? This article kind of stops short and seems to just be saying, "get a lawyer before you sign anything," which I've heard before. How would I know if a lawyer would be able to help improve the offer?